Process and device for simulated moving bed separation with a reduced number of large diameter valves

Abstract

The invention concerns a simulated moving bed (SMB) separation device and process comprising a column, beds A_i of adsorbent separated by plates P_i with a single distribution and extraction network for fluids, in particular feed F, desorbant D, raffinate R and extract E, and a plurality of two-way valves for distribution of said fluids, said valves being limited in number and in particular with dimensions that are smaller than in the prior art. According to the invention, the column is divided into a plurality of sectors S_k with 2 superimposed plates, each sector S_k comprising an external principal bypass line L_k connected to each plate P_i of S_k via a large diameter plate valve V_i and an external secondary bypass line M_k comprising a small diameter valve V_Mk connected to the adjacent sector S_k−1. Each line L_k comprises a flow limitation means, and is connected to each of the fluid networks F, D, R, E via a single large diameter valve for sequential supply or withdrawal of the corresponding fluid F, D, R or E to or from the sector Sk under consideration.

Description

FIELD OF THE INVENTION[0001]The invention relates to the field of separation of natural or chemical products which are difficult to separate by distillation. A family of processes and associated devices is used which are known as “chromatographic” or “simulated moving bed” or “simulated counter-current” or “simulated co-current” separation devices which we shall hereinafter term “SMB”.[0002]A non-exclusive list of the fields concerned is:[0003]separation of normal paraffins from branched paraffins, naphthenes and aromatics;[0004]olefin / paraffin separation;[0005]separation of para-xylene from other isomers in C8 aromatics;[0006]separation of meta-xylene from other isomers in C8 aromatics;[0007]separation of ethylbenzene from other isomers in C8 aromatics.[0008]In addition to the refinery and petrochemicals plant, there are may other applications, including glucose / fructose separation, the separation of positional isomers of cresol, optical isomers, etc.PRIOR ART[0009]SMB chromatograp...

AI Technical Summary

Benefits of technology

[0038]In accordance with the invention, “plate valves” are also provided, i.e. a large diameter valve, respectively Vi or Vi+

Problems solved by technology

A generic problem with all SMB devices is minimizing the pollution generated by the liquid present in the various zones and volumes of the supply and withdrawal circuits for the fluids and plates during modifications to the supply and withdrawal points during operation of the SMB.

Mixing or circulation over a short time interval of fluids with substantially different compositions thus introduces a deviation from the ideal operation, which proscribes discontinuities in composition.

A further problem may reside in any re-circulation between different zones of the same pla

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